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.Dd April 22, 2021
.Dt BUS_CHILD_LOCATION 9
.Os
.Sh NAME
.Nm BUS_CHILD_LOCATION
.Nd "obtain the location of a child on the bus."
.Sh SYNOPSIS
.In sys/param.h
.In sys/bus.h
.In sys/sbuf.h
.Ft void
.Fn BUS_CHILD_LOCATION "device_t dev" "device_t child" "struct sbuf *sb"
.Sh DESCRIPTION
The
.Fn BUS_CHILD_LOCATION
method returns the location of the
.Dv child
device.
This location is a series of key=value pairs.
The string must be formatted as a space-separated list of key=value pairs.
Names may only contain alphanumeric characters, underscores ('_') and hyphens ('-').
Values can contain any non-whitespace characters.
Values containing whitespace can be quoted with double quotes ('"').
Double quotes and backslashes in quoted values can be escaped with backslashes ('\').
.Pp
The location is defined as a series of characteristics of the
.Dv child
device that can be used to locate that device independent of what drivers are
attached.
Typically, these are slot numbers, bus addresses, or some topology formation.
Where possible, buses are encouraged to provide locations that are stable from
boot to boot and when other devices are added or removed.
A location is not dependent on the kind of device at that location.
.Sh SEE ALSO
.Xr bus 9 ,
.Xr device 9
